Process for forming hollow costume jewelry articles coated with a film of precious metal or metallic alloy

ABSTRACT

A process therewith, with the electro-deposition method, a not precious metal or metallic alloy “shell” ( 2 ) is produced, openings ( 3 ) are made therethrough the low flux ( 1 ) is made to drip outside by melting, then metallic “plugs” ( 4 ) are applied by brazing, then the coating is made with galvanic bath with a precious metal or metallic alloy film ( 5 ).

BACKGROUND OF THE INVENTION

The invention relates to a process for forming hollow costume jewelleryarticles coated with a precious metal or metallic alloy, therefore notprecious metal articles which are usually bulky, empty and then light,directed to the ornamental and fashion field.

Ornamental articles made of not precious metal are known, such as forexample copper and the alloys thereof, zama and still other metals,usually produced by microcast, therefore full and, if bulky, heavy to beworn. In order to overcome such last inconvenient, due to the fact thatthe articles are bulky and heavy, they are produced with the castingprocess therewith, starting from a thin metallic plate, two shells areimplemented which are then coupled therebetween and, at last, weldedalong the seam. In this way the implemented item results to berelatively light.

The articles produced by microcast and those produced by casting andwelding are cleaned and degreased onto the surface, then usually coatedwith a copper layer, or a layer of different metal, by means of agalvanic bath; at last, they are coated with a precious layer byelectrolysis so as to make them to appear brilliant and precious.

The known procedures in the first case produce heavy articles which canbe used then for very small ornamental articles. In the second case,even if they are relatively light, they require expensive moulds and acomplex subsequent processing. In one case or in the other one thefinished costume jewellery articles result to be relatively expensiveand therefore not always easy to be marketed.

In the precious metal field, gold and silver in particular, the thickarticles are usually produced with the electro-deposition process. Suchmethod provides to implement with a current-conducting product having alow melting temperature, hereinafter called “low flux” for brevity, amodel reproducing the item to be implemented, then by means of anelectrolytical process it is coated with a thick layer of preciousmetal, then several holes are made therein. The item is then heated atthe melting temperature of the low flux therewith the core thereof ismade, of about 200-250° C. in order to allow to empty thereof by dippingoutside through said holes. The low flux could be then recovered andtherefore used again. Once performed the emptying procedure, the lowflux traces remained inside the item are removed with a chemical bathsuitable to melt it so as not to alter the title of the golden “shell”,or any other precious metal therewith the article to be constructed ismade. The so-emptied article will be polished and/or subjected tofinishing to be then marketed.

In the so-produced precious metal items the holes are visible, which atfirst have been used to drip the low flux brought to melting, then toallow to melt into the acid bath, wherein the low flux is dipped, thelow flux traces which have remained inside the ornamental articleitself, then to remove them so as not to alter the title thereof.

Such method cannot be performed in the production of costume jewelleryarticles made of copper alloy since the acid bath therethrough the lowflux traces remained inside the “shell” are removed would corrode themand would bring into solution also the copper and the alloy thereof,thus destroying the “shell” reproducing the article to be implemented.

Furthermore, the gilding with an electrolytical bath cannot be performedas the low flux remained inside the “shell” would melt into the bath andit would make ugly the obtained gilting which would result to be ofspotted type. Furthermore, such galvanic bath could not be used any moreto perform the gilting of other precious metal items since the dissolvedlow flux would hinder the implementation thereof, it would render thesurface spotted and it would alter the title of the precious articlessubjected to gilting. All this does not make possible the production ofitems made of copper, or copper alloy, with the electro-depositionprocess and with final gilting of the surface thereof.

SUMMARY OF THE INVENTION

An aim of the present invention is to detect the process therethroughthe implementation of hollow bulky ornamental articles is made possible,constituted by a not precious metal or metallic alloy shell, withoutopenings, uniformly coated with a layer of precious, or howevervaluable, metal.

Another aim of the present invention is the production of itemstherewith the human body can be adorned, or accessories in the fashionfield, implemented with not precious metal or metallic alloy resultingto be hollow and therefore light and be coated with a thin layer ofprecious, or however valuable, metal which makes them of great value.

At last, another aim of the present invention is the production of itemsmade of not precious metal or metallic alloy, copper and the alloysthereof in particular, appearing to be without unaesthetic holes ontothe surface. The invention which has allowed to achieve such resultsconcretizes in a process constituted by a sequence of steps providing:

-   -   implementing the model in conducting material with low-melting        and low-flux temperature;    -   coating by electrolysis said low flux model with copper, the        alloys thereof or other not precious metal or metallic alloy, to        implement a coating “shell” reproducing the shape of the model;    -   implementing openings onto the coating “shell” made of not        precious metal or metallic alloy until reaching the low flux        inner core;    -   heating the coating “shell” and emptying the low flux content        thereof through said openings;    -   filling said openings with conducting metallic members        (“plugs”), resorting to brazings, then weldings with low-melting        temperature weld metal;    -   cleaning-smoothing the “shell” at least in the places wherein        the filling members have been applied by brazing;    -   coating by electrolysis the metallic “shell” with a layer of        golden alloy film or however with a precious metal film.

Furthermore, the invention relates to the so-obtained product whichresults to be bulky, light and with uniform surface, without holes,coated with precious, or however valuable, metal or metallic alloy whichmakes it to appear of high quality.

Such invention results to be advantageous since it allows implementingcostume jewellery ornamental articles with however shaped surfaces,without unaesthetic holes, light and bulky appearing to be made ofprecious, or however valuable, metal or metallic alloy, thereforehigh-quality ornaments. It results to be advantageous since the openingsor holes made onto the “shell” can also be relatively big, so as to makerapid the emptying process by melting the low flux core, with the almostcomplete recovery of the same to be used again. It results to beadvantageous as it is not provided to resort to any phase with acidcoming in contact with the low flux, therefore any risk of pollutingwith low flux the used acid bath is avoided. It results to beadvantageous since the application of “plugs” onto the openings protectsthe bath, therewith the electrolytical coating is made, from the lowflux pollution and the coating obtained onto the produced articlesresults to be uniform and perfect, like the one performed onto full notprecious metal articles or onto those obtained from cast, coupled andthen welded shells.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in details hereinafter by referring tothe preferred embodiment solution and to the schematic drawingsillustrating it, wherein:

FIG. 1 is the front view of a low flux annular structure, sectioned by amedian plane;

FIG. 2 is the front view of the annular structure of FIG. 1, coated witha “shell” obtained by electro-deposition with a not precious metal ormetallic alloy, sectioned by a median plane;

FIG. 3 is the front view of the structure of FIG. 2 whereon two openingsor emptying holes have been made, therewith the low flux inner core isreached;

FIG. 4 is the front view of the structure of FIG. 3 once it has beenemptied by melting the inner or low flux core and the emptying openingshave been filled with brazed metallic “plugs”;

FIG. 5 is the front view of the structure of FIG. 4 once the outerportions of the “plugs” have been smoothed, then the product has beencoated by electrolysis with a precious metal or alloy film;

FIG. 6 is the front view of the back of the annular structure of FIG. 5,from the side wherein there are the “plugs” hidden to the sight by thecoating film;

FIG. 7 exemplifies a pendant implemented with the described process andwherein, apart from the “plugs”, the attachment annular structure hasbeen applied before proceeding to coating with the precious film throughthe electrolytical bath.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

It is understood that the drawings are of schematic type and they areprovided only with the purpose of facilitating the comprehension of theinvention and in particular the phase sequence therethrough the finishedarticle is obtained, without constituting any limitation therefor.

Then, the invention substantially relates to the process therethroughthe forming of articles which are destined to the costume jewellery andfashion fields is made, which articles are implemented with not preciousmetals or metallic alloys and copper and the alloys thereof inparticular, coated with a precious, or however valuable, metal ormetallic alloy film, such as for example gold and the alloys thereof,therethrough said articles are made to have a valuable aspect and toappear as precious, even if they result to have a low cost and to belight, even when they are bulky.

The subject process provides a step wherein the model 1 is manufacturedwith low flux, that is electric current conducting material with lowmelting temperature, therefore passing from the solid state to theliquid state at a temperature usually ranging from 200 and 250° C., suchas for example the alloys used in the electro-deposition process in theproduction of precious metal articles.

In a subsequent step the coating of said model 1 is made byelectrolytical way with not precious metal or metallic alloy, withcopper or the alloys thereof in particular, until originating a “shell”2 with a thickness usually comprised between one and five tenths ofmillimiter.

Openings 3 are made onto the so-obtained composite item, which openingscross the coating “shell” 2 and reach the model 1 or low flux innercore. Such openings 3 are implemented in places preferably with smoothsurface and in positions so as to favour the emptying by dripping of theinner core when it is brought in the melt phase. The openings 3 aremade, for example, with drills and however preferably with profilesection thereof with the trapezoid shape, as exemplified in FIG. 3 inthe enclosed drawing.

Then, a phase follows wherein the model 1 coated by the shell 2 isheated until reaching the low flux melting temperature and it is keptthere in a position suitable to allow the outcoming thereof untilemptying the “shell” 2 itself, in case with shakings or motions aimed ataccelerating the emptying process.

An incomplete emptying process is however tolerated, not altering thequality of the finished product, except for a greater weight thereof andan incomplete recovery of the low flux material to be used in theproduction of the subsequent models.

At this point, with the very small filling materials or metallic “plugs”4, the openings 3 in the “shell” 2 are filled, stabilized by brazing,that is with melting with low melting temperature weld metal, such asfor example tin.

Therefore, the cleaning-smoothing is made at least of the places whereinthe metallic filling materials or “plugs” 4 have been applied so as tomask the presence thereof or, however, to not determine any formalvariation of the surfaces wherein said “plugs” 4 have been inserted andwithout altering the metallic continuity of the produced articlesurface.

Once reached such state, after having made the washing-degreasing of theitem, the coating thereof is made with an electrolytical process, bydepositing onto the surface of the same a finishing layer 5 of precious,or however valuable, metal or metallic alloy, with a thickness usuallyin the order of a micron, until making the product to assume surfaceuniformity and constant colour and however the wished image.

Depending upon the article to be implemented, in the phase wherein themetallic “plugs” 4 are applied onto the emptied not precious “shell” 2,at the emptying openings 3, it is possible to apply, still by brazing,one or more applicable members, such as a hooking and/or supportingmember in the place wherein the “shell” will have to interact with outermeans, for example an attachment annular structure 6, in case the itemimplements a pendant as exemplified in FIG. 7, a pin therewithimplementing the ear-rings' attachment, a base for the snap-closure or aclip, etc.

The application of the “plugs” and of the hooking and/or supportingmembers is usually made by brazing with weld metal melting at lowtemperature so that there are not considerable thermal stresses onto the“shell” and at the same time without determining a heating of the aircontained inside the “shell” itself, so as to cause the arising ofpressures which, if relatively high, could bring to deformation or evento the burst of the item itself.

In case the metal or metallic alloy therewith the “shell” 2 isimplemented be not compatible with the precious metal or metallic alloytherewith one wishes to finish the item, said shell 2 is subjected to anelectrolytical galvanic bath therewith it is coated by a very thin layerof the metal which makes it compatible with the final coating.

The ornamental articles implemented with the described process can behowever diversified. They could be bracelets, necklaces, ear-rings,brooches, buckles, fanciful pendants and others, and all of them will becharacterized by a usually broad volume, lightness, surface uniformityand therefore absence of unaesthetic holes or openings; furthermore,they will have a coating with electro-deposited finishing layer, usuallymade of precious metal or metallic alloy.

The described phase sequence could also be subjected to small variationsduring execution, however without altering the invention logic which hasallowed the production of bulky and light articles of costume jewelleryand fashion, then said variations being comprised within the protectionscope as defined by the following claims.

1. A process for forming hollow costume jewellery articles coated with alayer of precious metal or metallic alloy constituted by: a step whereinthe model (1) is manufactured with a current-conducting material withlow melting temperature (low flux); a step wherein the coating of saidmodel (1) is made by electrolytical way with copper or alloys thereof,or however with a not precious metal or metallic alloy, to implement a“shell” reproducing the shape of the model (1); a step wherein theopenings (3) onto the coating “shell” (2) are made until reaching themodel (1) or low flux inner core; a heating step therewith the coatedmodel (1) is heated until reaching the low flux melting temperature andit is kept there in a position suitable to allow the melt low fluxitself to come out through the openings (3) until emptying the “shell”(2), as well as characterized by: a step wherein filling materials ormetallic “plugs” (4) are applied at least onto the openings (3) in the“shell” (2) and fastened there by brazing; a step of cleaning-smoothingat least of the places wherein the metallic filling materials (4) and incase the hooking and/or supporting members (6) have been applied, bybrazing: a step wherein the coating of the “shell” (2) is made withelectrolytical process, by depositing onto the same a finishing layer(5) of precious, or however valuable, metal or metallic alloy.
 2. Theprocess, as claimed in claim 1, characterized by a step wherein apartfrom the metallic “plugs” (4) at the openings (3) a hooking and/orsupporting member (6), or other interaction member, is applied onto the“shell” (2) in the place wherein the “shell” (2) has to interact withouter means.
 3. The process, as claimed in claim 1, characterized by astep wherein the application of the metallic “plugs” (4) and of thehooking and/or supporting members (6) is made by brazing with weld metalmelting at low temperature.
 4. The process, as claimed in claim 1,characterized by a step wherein the “shell” (2) is subjected to anelectrolytical process therewith the outer surface thereof is madesuitable to receive the finishing layer (5) of precious, or valuable,metal or metallic alloy.
 5. Ornamental articles, implemented with theprocess as claimed in claim 1, characterized by an empty structure or“shell” obtained by electro-deposition, with said “shell” beingimplemented in copper or the alloys thereof or other not precious metalsor metallic alloys, without openings (3) and coated with a finishinglayer (5) made of electro-deposited precious metal or metallic alloy.